Abstract: El Niņo brings widespread drought to the tropics. Stronger or more frequent El Niņo events in the future could exacerbate drought risk in highly vulnerable tropical areas. Even if the frequency and intensity of El Niņo events do not increase in the 21st century, more generalized warming of the tropical Pacific may still produce a tropical teleconnection resembling that associated with present-day El Niņo conditions. This study investigates the patterns, magnitude, and spatial extent of El Niņo induced tropical droughts during a control period in 20th century seasonal forecasts, which have updated realistic initial conditions but fixed greenhouse gases, and in 20th century climate change simulations, which have realistic greenhouse gases evolution but no observational updates. El Niņo-induced droughts for the 21st century climate change projections are also investigated.

As reported in previous studies seasonal forecast models predict El Niņo-induced precipitation teleconnection patterns in the 20th century in good agreement with the observations. Droughts observed during El Niņo years in northern South America, and parts of southern Africa, Indonesia and north Australia are consistently captured by seasonal forecast models. Climate change models that produce oceanic ENSO variability exhibit realistic El Niņo-induced drought patterns in the 20th century, and those teleconnection patterns are not projected to change in the 21st century due to global warming. In combination with projected trends in precipitation, however, drought conditions are exacerbated in some regions and ameliorated in others. An example of spatial calibration of 21st century projections of ENSO teleconnections using 20th century information provides a potentially more reliable estimate of drought risk patterns projected for the 21st century.